Industrial negatively charged c-Si surface passivation by inline PECVD AlOx

A high-rate plasma-enhanced chemical-vapor-deposition (PECVD) process for aluminium oxide layers was developed at low temperatures to reduce minority carrier recombination on p-type c-Si surfaces. A maximum effective surface recombination velocity Smax of 10 cm s-1 was obtained on highly doped (1 ? cm) p-type substrates. The optical constants n and k, the atomic composition of the layer, the surface charge density Qox and the interface defect density Dit of the PECVD AlOx layers were measured. Our main goal was to transfer the aluminium oxide deposition process from ALD technique to an industrial inline PECVD system with the aim to implement highquality field-effect passivation into a large and fast deposition system applicable in the industry. PECVD of AlOx can be transferred to already existing industrial inline systems to allow for a fast spreading of the technology. Excellent passivation quality can be obtained with AlOx PECVD deposition with deposition rates at least one order of magnitude higher compared to ALD. First cell results applying a close-to-industry approach with screen-printed front and rear metallisation on CZ-Si substrates (1252 mm2) showed VOC values above 630 mV.